1. Field of Invention
The present invention generally relates to cellular phones and specifically to hands free models of cellular phones that leverage external peripherals.
2. Prior Art
Cellular phones exist in various form factors and functionalities. The form factor of a device is its linear dimensions and physical configuration. The features of cellular phones may be divided into low end, mid-range and high end phone categories. Low end phones offer basic voice calling features, mid-range phones enable picture exchange and high end phones are completely programmable that offer full multimedia functionality. These categories offer users a broad range of form factors that balance size, weight and usability metrics.
With varying form factors and functionalities, cellular phones have become devices of choice for persons to carry to stay connected. This in turn has motivated cellular phone manufacturers to incorporate much additional functionality into cellular phones, making them multi-purpose devices, while reducing costs.
With evolution of cellular phones into multi-purpose devices, usage of cellular phones will increase and in particular usage in automobiles is expected to increase as well. Providing new functionality in hands free mode in an automobile is a big challenge.
Currently there are several cellular phone accessories that enable hands free usage of cellular phones within automobiles but each is limited to a fixed functionality. But with programmable cellular phones, new functionality can be added with ease, and existing fixed functionality accessories will not be usable with new functionality. There is a need for a solution that can support new functionality and be forward compatible in order to provide new cellular phone functionality in an automobile. An accessory that can support new functionality in a forward compatible manner and in hands free mode of operation does not exist today. Hence providing new cellular phone functionality into automobiles is a major issue that needs to be resolved. The present invention addresses this issue by providing a solution whereby new cellular phone functionality can be made available in hands free mode of operation in an automobile at low cost and high operational efficiency. Examples of new functionality could include but not limited to streaming and non-streaming multimedia applications, remote surveillance and data gathering.
Usage of cellular phones in automobiles has been found to be highly distractive to drivers. Accidents have been attributed to cellular phone conversations during driving, and, as a result, several countries prohibit usage of cellular phones while driving, or prohibit usage while driving without a hands free mode of operation. This problem of cellular phone usage in an automobile is likely to worsen as usage levels increase with more functionality of high end phones unless there is a hands free solution that can accommodate new functionality as well.
One solution to above problem is to prohibit usage of cellular phones in automobiles completely.
Solutions that completely prohibit cellular phone usage are extremely difficult to justify in countries where people have to drive long distances and spend much time commuting. Any emergency call during periods of driving could be missed and contribute to other problems. Similarly, periodic calls may need to be made, for example, to check on an old parent as people may schedule such calls while driving to optimize stressed schedules. Enforcing such rules will be difficult to implement in countries with several thousand miles of roads to cover. Thus, prohibiting cellular phone usage in automobiles is impractical and may trade one problem for another.
Using a hands free system is the only practical alternative that reduces the stress of holding a cellular phone with one hand thereby improving driving focus levels. But with evolving cellular phone functionality, hands free systems must also evolve to provide newer functionality.
Hands free systems have been in existence for several years. Some cellular phones provide speaker phone functionality with a speaker component to enable hands free operation. But these phones are not usable on noisy roads or in a car poorly shielded for noise such as a convertible with a closed soft top. Most speakers that are embedded in phones are too small to provide high quality base and treble necessary for a clear conversation or high quality music.
Other hands free systems are available as attachments to cellular phones. Such systems provide an external microphone and speaker that is connected using a cable to cellular phones to enable hands free operation. But these systems suffer from similar issues of providing lower quality audio because of limited speaker size and cater only towards voice applications. U.S. Pat. Nos. 6,687,513 and 6,411,823 propose such solutions.
To solve speaker quality issues, there are systems that use an audio cassette adaptor to connect a cellular phone to audio system of an automobile to transfer incoming voice to speakers of an automobile. This solves a problem of incoming audio being heard via automobile speakers, but outgoing audio will suffer from echo effects as most cellular phones that do not support hands free mode do not support echo cancellation. Even in cases where cellular phones support hands free mode and corresponding echo cancellation algorithms, such algorithms are tuned to work with embedded speaker components which have lower amplitude and frequency range. Hence heavily amplified audio from automobile speakers will still exhibit echo effects.
Note that, a connection between a cellular phone and a cassette adaptor may be a wired or wireless connection. Irrespective of connection type, unless a cassette adaptor provides its own set of echo cancellation algorithms, a hands free mode operation for just voice applications using a cassette adaptor is impractical.
Also, a wired cassette adaptor is not practical to be used in all automobiles since audio cassette players in automobiles have different mechanisms to load a cassette. Some audio cassette players will have front loading and some will have side loading mechanism. Some may have an opening in the front and some may be fully covered. Given these differences it is not always possible to draw out a wire from a cassette adaptor to a cellular phone without affecting the performance of an audio cassette player. Hence there is a need for a wireless solution.
U.S. Pat. No. 6,058,319 proposes such a cassette adaptor based solution and suffers from above mentioned shortcomings.
This leads to a possible solution that is a wireless cassette adaptor that provides echo cancellation to inter-operate with a cellular phone. Such systems are in existence by using bluetooth as a wireless networking protocol between cellular phones and cassette adaptors. Wireless cassette adaptors may use analog or digital wireless signals to communicate with cellular phones. Analog wireless signals suffer from low bandwidth and security limitations and hence unusable to transfer private conversations. Whereas digital wireless signals such as bluetooth provide relatively higher bandwidth, they are expensive to implement in terms of battery usage.
In particular, transferring full duplex voice can be easily accommodated using a 64 kilo bits per second pulse code modulated signal, but transferring multimedia content from high end phones, including high quality stereophonic audio requires several megabits of bandwidth. For example, pulse code modulated samples (PCM) with 24-bits of data sampled at 96 kilo hertz requires a 4.39 mega bits per second data rate. Currently, the maximum data rate a bluetooth chipset can provide is 3 mega bits per second which is insufficient for high quality audio transfer. Also, as data rates get higher, digital radio frequency (RF) circuitry consumes substantially more power thereby decreasing battery life.
Hence it can be seen that a wireless cassette adaptor cannot support a full featured high end phone adequately because of requirements for voice and multimedia applications.
To solve bandwidth issues with a wireless accessory, an alternative may be to embed a wireless cassette adaptor with decoding functionality to decode digitally encoded music that is transferred at lower rate. Such cassette adaptors will have at most one or two decoders to maintain cost effectiveness with respect to cellular phones. There are several available digital music formats including advanced audio coding (AAC), motion picture expert group level three (MP3), AU, WAV, OGG etc. Since music formats continue to evolve, a wireless cassette adaptor that has an ability to decode only a few formats will be ineffective with new digital data formats. Hence such an alternative is not forward compatible with evolving functionality of cellular phones that provide multimedia functionality and beyond.
Apart from bandwidth issues associated with a wireless accessory, communication protocols are also important issues. A wireless accessory to a cellular phone must implement standard protocols such that accessories from different vendors may interoperate with different cellular phones. This leads us to the next problem that exists in wireless protocols such as bluetooth. Currently bluetooth supports three protocols, called profiles, related to audio accessories including: headset profile, hands free profile and audio profile. The headset profile enables any wireless accessory to behave like a headset to support full duplex voice transfer with cellular phones. The hands free profile enables an accessory to behave like a speakerphone with a key addition of echo cancellation algorithm inside the accessory. The audio profile enables stereophonic audio to be transferred at a limited rate with a limited codec set. Notice that as new functionality is added, new profiles need to be added to both cellular phones and corresponding accessories. Since these profiles are defined and controlled by standard bodies it may take a very long time before any profile is standardized, thereby contributing to slow evolution of accessory functionality.
As new functionality is added, a new profile or a protocol is needed to communicate between a wireless accessory and a cellular phone. This is an impractical and non-scalable solution because of non-deterministic time intervals for standardized profiles. On the other hand, new generations of high end cellular phones offer much new functionality including the ability to download content with new data formats. However new data formats can only be communicated to an accessory if a standard exists for such a data format communication. Hence a digital wireless accessory is not a forward compatible option that can support both limited and evolving functionality of all ranges of cellular phones
Additional examples of protocol evolution problems can be seen with introduction of internet protocol multimedia subsystem (IMS) that introduces new interactive services such as push-to-talk over cellular (PoC) and text messaging. These services require new usage patterns from wireless accessories but this can be done only if both the wireless accessory and the cellular phone understand a common data format and behavior pattern, implying a need for a new profile or protocol.
Wireless accessories suffer from similar problems to support even existing features of cellular phones. For example, voice dialing is a common feature in most cellular phones today, but this is not supported by a bluetooth enabled headset, since current headset and hands-free profile support voice interaction only for a full duplex phone call and not for voice dialing. Similarly if a short message service message (SMS) has been received by the cellular phone, there is no way to dispatch this message to a wireless accessory without a new profile.
Hence it can be seen that wireless accessories have two limitations including lack of support for decoding new data formats and lack of standardized protocols to support new application features. That is, a wireless accessory is not forward compatible with new data format or protocols.
In summary, a new application cannot be accommodated without standardized wireless data exchange and behavior protocols or profiles. Adding more functionality to an accessory to keep abreast of evolving functionality of cellular phones does not solve all limitations mentioned so far and also increases the accessory cost substantially. Hence a wireless cassette adaptor is an impractical solution with regards to forward compatibility.
U.S. Pat. Nos. 6,636,749, 6,542,758 propose Bluetooth based hands-free adaptor and they suffer from shortcomings mentioned above.
There are also systems that are fully integrated with car audio systems but such systems are expensive to install into an older automobile and add at least a thousand dollars extra as an option for a new automobile. These also suffer from forward compatibility issues apart from cost and installation issues.
U.S. Pat. No. 6,847,833 proposes a hands-free system for supporting multiple devices and a connectivity solution for integrating with car stereo systems. The car stereo connectivity solution calls for modifications to car stereo thereby increasing the installation cost. Additionally, this proposed solution does not address any of the forward compatibility issues, such as supporting new media formats or supporting new applications as they become available in mobile phones.
U.S. Pat. No. 6,701,161 proposes a multimedia unit for automotive vehicles. This prior art offers a comprehensive in-vehicle communication and vehicle control solution. It is more suited for newer premier model automobiles because of the cost involved. Additionally, this solution is simply not viable to be installed as after market solution for existing cars to due installation complexities and cost involved. Some systems provide a frequency modulation (FM) transmitter attachment to enable connectivity with automobile audio system. But these systems are limited by FM bandwidth and insecure transmission format permitting persons in the neighborhood to hear private conversations.
U.S. Pat. No. 6,484,040 proposes a hands-free solution for in-vehicle use that uses infrared or radio (FM/AM) radio communication between in-car audio equipment and mobile phone. Existing car audio systems don't support infrared communication. Installing new audio system will increase the cost of the solution. Radio based solutions are neither secure nor of good audio quality. Additionally, this solution will not be able to extend hands-free support to new multi-media applications as they become available in mobile phones. U.S. Pat. No. 6,397,086 which also calls for infrared communication between car audio and phone also suffers from similar shortcomings. U.S. Pat. No. 6,304,764 which calls for cassette adaptor or FM transmitter also suffers from the same limitations. U.S. Pat. No. 6,163,711 which calls for FM transmitter also suffers from the same limitations.
U.S. Pat. No. 3,991,369 proposes a cartridge system providing radio transceiver capability. This describes an accessory for an analog half duplex communication apparatus. It is not a single device solution for hands free cellular phone operation. Another difference to note is that both antenna and microphone are external attachments unlike the present invention. Hence it does not address any of said issues related to hands free forward cellular phone system.
Based on the above analysis of existing and potential solutions that offer a hands free system to a cellular phone in an automobile, it is clear that all such solutions suffer from at-least one of limitations mentioned below:                a) Poor quality because of limited speaker size and performance metrics.        b) Hanging wires causing potential operation problems.        c) Lack of forward compatibility with new data formats because of cost considerations.        d) Lack of forward compatibility with new applications because of slow evolution of new wireless accessory profiles.        e) Poor battery performance with higher data rates with a wireless accessory.        f) High installation cost.        g) High cost of accessories.        
As can be seen from above, all known prior art suffers from at least one of said limitations and hence there is a need for a new hands free system that does not suffer from above limitations and offers a full featured, forward compatible hands free system.